1. Field of Invention
The present invention relates to a high voltage (>400V) device, and more generally to a power lateral double diffusion MOS (power LDMOS) device having a smaller terminal region.
2. Description of Related Art
As the semiconductor industry is developed with time, a high voltage device such as a power LDMOS device has been widely applied in many electronic systems. Generally speaking, a power LDMOS device includes a plurality of source regions, a plurality of drain regions and a plurality of gates. The source regions and the drain regions are disposed alternately. A gate is disposed between the neighboring source and drain regions. Further, the power LDMOS device has an active region and a terminal region.
The corner portion of the terminal region has the least resistance to high voltage, and the electric filed is too strong thereat. It is known to increase the design rule so as to avoid excessive concentration of electric field. The vertical distance from ends of the drain regions in the terminal region to the periphery of the source region in the terminal region can be enlarged to at least greater than 80 μm. However, this method would waste a significant amount of area and reduce the competitiveness.